<!DOCTYPE html>
<html>
<!-- Created by GNU Texinfo 7.1, https://www.gnu.org/software/texinfo/ -->
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<!-- This file documents the use of the GNU compilers.

Copyright © 1988-2023 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Funding Free Software", the Front-Cover
Texts being (a) (see below), and with the Back-Cover Texts being (b)
(see below).  A copy of the license is included in the section entitled
"GNU Free Documentation License".

(a) The FSF's Front-Cover Text is:

A GNU Manual

(b) The FSF's Back-Cover Text is:

You have freedom to copy and modify this GNU Manual, like GNU
     software.  Copies published by the Free Software Foundation raise
     funds for GNU development. -->
<title>C99 Thread-Local Edits (Using the GNU Compiler Collection (GCC))</title>

<meta name="description" content="C99 Thread-Local Edits (Using the GNU Compiler Collection (GCC))">
<meta name="keywords" content="C99 Thread-Local Edits (Using the GNU Compiler Collection (GCC))">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<meta name="viewport" content="width=device-width,initial-scale=1">

<link href="index.html" rel="start" title="Top">
<link href="Indices.html" rel="index" title="Indices">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="Thread_002dLocal.html" rel="up" title="Thread-Local">
<link href="C_002b_002b98-Thread_002dLocal-Edits.html" rel="next" title="C++98 Thread-Local Edits">
<style type="text/css">
<!--
a.copiable-link {visibility: hidden; text-decoration: none; line-height: 0em}
kbd.key {font-style: normal}
span:hover a.copiable-link {visibility: visible}
ul.mark-bullet {list-style-type: disc}
-->
</style>


</head>

<body lang="en_US">
<div class="subsection-level-extent" id="C99-Thread_002dLocal-Edits">
<div class="nav-panel">
<p>
Next: <a href="C_002b_002b98-Thread_002dLocal-Edits.html" accesskey="n" rel="next">ISO/IEC 14882:1998 Edits for Thread-Local Storage</a>, Up: <a href="Thread_002dLocal.html" accesskey="u" rel="up">Thread-Local Storage</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Indices.html" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<h4 class="subsection" id="ISO_002fIEC-9899_003a1999-Edits-for-Thread_002dLocal-Storage"><span>6.64.1 ISO/IEC 9899:1999 Edits for Thread-Local Storage<a class="copiable-link" href="#ISO_002fIEC-9899_003a1999-Edits-for-Thread_002dLocal-Storage"> &para;</a></span></h4>

<p>The following are a set of changes to ISO/IEC 9899:1999 (aka C99)
that document the exact semantics of the language extension.
</p>
<ul class="itemize mark-bullet">
<li><cite class="cite">5.1.2  Execution environments</cite>

<p>Add new text after paragraph 1
</p>
<blockquote class="quotation">
<p>Within either execution environment, a <em class="dfn">thread</em> is a flow of
control within a program.  It is implementation defined whether
or not there may be more than one thread associated with a program.
It is implementation defined how threads beyond the first are
created, the name and type of the function called at thread
startup, and how threads may be terminated.  However, objects
with thread storage duration shall be initialized before thread
startup.
</p></blockquote>

</li><li><cite class="cite">6.2.4  Storage durations of objects</cite>

<p>Add new text before paragraph 3
</p>
<blockquote class="quotation">
<p>An object whose identifier is declared with the storage-class
specifier <code class="code">__thread</code><!-- /@w --> has <em class="dfn">thread storage duration</em>.
Its lifetime is the entire execution of the thread, and its
stored value is initialized only once, prior to thread startup.
</p></blockquote>

</li><li><cite class="cite">6.4.1  Keywords</cite>

<p>Add <code class="code">__thread</code>.
</p>
</li><li><cite class="cite">6.7.1  Storage-class specifiers</cite>

<p>Add <code class="code">__thread</code> to the list of storage class specifiers in
paragraph 1.
</p>
<p>Change paragraph 2 to
</p>
<blockquote class="quotation">
<p>With the exception of <code class="code">__thread</code>, at most one storage-class
specifier may be given [&hellip;].  The <code class="code">__thread</code> specifier may
be used alone, or immediately following <code class="code">extern</code> or
<code class="code">static</code>.
</p></blockquote>

<p>Add new text after paragraph 6
</p>
<blockquote class="quotation">
<p>The declaration of an identifier for a variable that has
block scope that specifies <code class="code">__thread</code> shall also
specify either <code class="code">extern</code> or <code class="code">static</code>.
</p>
<p>The <code class="code">__thread</code> specifier shall be used only with
variables.
</p></blockquote>
</li></ul>

</div>
<hr>
<div class="nav-panel">
<p>
Next: <a href="C_002b_002b98-Thread_002dLocal-Edits.html">ISO/IEC 14882:1998 Edits for Thread-Local Storage</a>, Up: <a href="Thread_002dLocal.html">Thread-Local Storage</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Indices.html" title="Index" rel="index">Index</a>]</p>
</div>



</body>
</html>
